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Axon terminals (also called terminal boutons, synaptic boutons, end-feet, or presynaptic terminals) are distal terminations of the branches of an axon. An axon, also called a nerve fiber, is a long, slender projection of a nerve cell that conducts electrical impulses called action potentials away from the neuron's cell body to transmit those ...
Postsynaptic potentials occur when the presynaptic neuron releases neurotransmitters into the synaptic cleft. These neurotransmitters bind to receptors on the postsynaptic terminal, which may be a neuron, or a muscle cell in the case of a neuromuscular junction. [1]
When the action potential reaches the presynaptic terminal, it provokes the release of a synaptic vesicle, secreting its quanta of neurotransmitter molecules. The neurotransmitter binds to chemical receptor molecules located in the membrane of another neuron, the postsynaptic neuron, on the opposite side of the synaptic cleft.
Both the presynaptic and postsynaptic sites contain extensive arrays of molecular machinery that link the two membranes together and carry out the signaling process. In many synapses, the presynaptic part is located on the terminals of axons and the postsynaptic part is located on a dendrite or soma .
This difference across the membrane is what the neuron uses to actually do the work of sending messages from the axon hillock of the neuron all the way down to the presynaptic terminal and then on to the postsynaptic terminal because of the release of neurotransmitter into the synaptic cleft. [3]
The presynaptic bouton has an efficiently orchestrated process to fuse vesicles to the presynaptic membrane to release neurotransmitters and regenerate neurotransmitter vesicles. This process called the synaptic vesicle cycle maintains the number of vesicles in the presynaptic bouton and allows the synaptic terminal to be an autonomous unit.
When the motor nerve is stimulated there is a delay of only 0.5 to 0.8 msec between the arrival of the nerve impulse in the motor nerve terminals and the first response of the endplate [7] The arrival of the motor nerve action potential at the presynaptic neuron terminal opens voltage-dependent calcium channels, and Ca 2+ ions flow from the ...
Neurotransmission (Latin: transmissio "passage, crossing" from transmittere "send, let through") is the process by which signaling molecules called neurotransmitters are released by the axon terminal of a neuron (the presynaptic neuron), and bind to and react with the receptors on the dendrites of another neuron (the postsynaptic neuron) a ...